Quick Write: Geologists have devised methods to estimate the ages of rocks in the Grand Canyon. Geologists have determined: The Earth is probably 4.5 billion years old. Kaibab Limestone is about 250 million years old. Muav Limestone is about 530 million years old. Under Muav Limestone is a layer of shale and then a layer of sandstone. The oldest rock layer in the Grand Canyon, found far under the Muav Limestone, is at least 1.7 billion years old. What events or processes do you think caused these rock layers to form? Reminders: -Scientist report due TOMORROW -Earth History Test 10/13/08 Rock Layer Formation Lesson #27

Draw a line under today’s quick write representing the end of today’s ideas. Leave the rest of your quick write page blank so we can come back to it later. 10/13/08 Rock Layer Formation Lesson #27

Which Grand Canyon rocks are sandstones? 10/13/08 Rock Layer Formation Lesson #27 Coconino Sandstone and Supai Sandstone How do we know a rock is sandstone? What is sandstone made of? Sandy (gritty, grainy) texture Sand comes off when two pieces rub together Acid soaks in Sand

Which came first, the sand or the sandstone? Support your answer with evidence. 10/13/08 Rock Layer Formation Lesson #27 Where could the sand have come from?

10/13/08 Rock Layer Formation Lesson #27 Available Materials per group: 1 plastic jar with lid 3 pieces of granite (common hard rock from mountain ranges) 2 hand lenses Rulers How could you conduct an investigation to see if sand really can come from broken-up pieces of rock? Take 7 minutes to plan with your group before getting any materials.

10/13/08 Rock Layer Formation Lesson #27 Try out your plan (3-5min)

10/13/08 Rock Layer Formation Lesson #27 STOP creating sand. Take out remaining large granite pieces. Collect your sand on a piece of white paper

10/13/08 Rock Layer Formation Lesson #27 Use hand lenses to closely observe the sand, remaining pieces of granite, and an unused piece of granite. Diagram the used granite, unused granite, and sand. Follow the ABCDs of scientific diagrams. (Accurate, Big, Colorful, Detailed) For example: Draw sand particles precisely using shading or color. Do not just make dots to represent sand. Label your diagram(s) with specific measurements, shapes/textures, and colors.

10/13/08 Rock Layer Formation Lesson #27

Earth History Test -Observation and Inference Determine if a given statement is an observation or inference -Calcite, Limestone, Shale, Sandstone - Know how to identify a rock as limestone, shale, or sandstone using acid - Know which type of rock contains calcite and how calcite reacts to acid. -Differential erosion - Know how differential erosion effects the shape of remaining rock - Infer if specific rock layers are harder or softer than surrounding rocks based on the landform left by differential erosion Additional Vocabulary: - rock column, correlation, plateau, rock layers, rock samples, formation